Nanogel is a colloid system which is uniformly dispersed into water with a particle size of 1˜1000 nm. The molecular chain structure of nanogel intermediates between branched polymer and network polymers, and the internal structure of which is cross-linking network. The cross-linking point among molecular chains of nanogel could be chemical point formed by chemical bond or physical point formed by interaction of hydrogen bond, static or hydrophobic interaction. Intelligent nanogel is a nanogel capable of responding on external stimuli, which is also known as stimuli-responsive nanogel. The external stimuli include change of temperature, dispersion medium pH and ionic strength, along with light, magnetic field and particular chemicals or biological substance.
Polyhedral oligomeric silsesquioxane (POSS for short) is a kind of caged-shaped organic-inorganic hybrid molecule being characterized by super-hydrophobicity, Macroligand efficiency and nano-size, which present particular thermal property, optical property, magnetic property and acoustic property. Therefore, POSS-based polymer is hailed as new generation of high-performance polymer.
In the last decade, intelligent nanogel shows attractive application prospect as Nanotechnology, biomedicine and intelligent material developed, and researches on its preparation, relationship between structure and property and application are getting more and more attention. Chinese patent No. CN102766267A discloses a method for preparing magnetic nanoparticle-containing chitosan hydrogel via adding magnetic nanoparticle dispersion into chitosan acetic acid solution and adding crosslinking agent for reacting to get the chitosan hydrogel. The entrapping method is simple; however, agglomeration and deposition of magnetic nanoparticle may occur during gel process, which may leads to misdistribution of magnetism. Chinese patent No. CN 102391603A discloses a method for preparing a novel magnetic polymer aquogel that iron ions are absorbed by sulfonate of aquogel under electrostatic interaction and then deposited via coprecipitation to generate Fe3O4 magnetic particles with a size of 50˜100 nm. The method overcomes the problem of magnetic maldistribution, but the size of sol is too big to be applied in biomedicine. Chinese patent No. CN103242494A discloses a method for preparing composite microgel with sensibility of temperature, pH and magnetic, wherein superparamagnetic Fe3O4 particle is prepared with initiate center on its surface which is embedded by thermo-sensitive monomer and pH-sensitive monomer via Sedimentation and polymerization to obtain the composite microgel. However, the problem of magnetic misdistribution also remains. Chinese patent No. CN103304826A discloses a method for preparing magnetic chitosan hydrogel, wherein N-methyl acrylamide chitosan is capable of curing to hydrogel in UV light for 30 to 120 seconds and magnetism-induced patterned assembly of microgel is realizable, however, the processes are too complicated to practical application.
There is no report about POSS-containing in-situ composite nanogel with magnetic responsiveness at present.